Machine for grinding and sifting wood pulp



De.; z3, 19,24.

v A. BIFFAR MACHINE FOR GRINDING AND-SIF'TING WOOD PULP Filed Aug. 22, 1921 Patented Der:e Z3, 1924i.,

ANDREAS BFFAR, 0F MILTENBERG, GERMANY.

:MACHINE FOR GRINDTNG AND SIETING 'WOGD ULP.

Application filed August 22, 1921. Serial No. 494,141.

(GRANTED UNDER THE PROVISIONS 0F THE ACT 0F MARGH 3, 1921, 41 STAT. L., 1313.)

' o all w wm t may concern Be it known that l, ANDREAS BIFFAR, a citizen of the German Empire, residing at lilliltenberg, Germany, have invented certain new and useful Improvements in Machinesv for Grinding and Sifting Wood Pulp (for which l have filed application in Germany on July 7, 1914, and in Sweden on August T, 1919), of which the following is a. specification.

My invention relates to the production of mechanical wood pulp for the manufacture of paper.

As is well known, the mechanical production of pulp for the paper manufacture is edected by grinding the wood by means of suitable grinders and thus reducing it to tine libres. From the grinder the pulp is conveyed to a container and from there into a sifting device, in which. the fine stuff is separated from the coarse stuff, the former being then conveyed to the dehydrating machine and the latter to a tank whence it is passed on to grinding rollers to be ground once more whereupon it is returned to the sifter. This method of manufacture of the pulp thus requires two nachines [and at least two pumps besides the grinder and each machine as well as the pumps must be provided with4 a drive of its own and requires separate attendance.

According to the present invention the production of wood pulp is considerably simplified by combining a sifting device with a grinding mill in such a manner that the coarse stuff ejected by the sifting device is conveyed by means of a channel into the grinding mill and hence returns into the siftcr.

lu the drawings affixed to this specifica.- tion and forming part thereof, two modifications of a combined sifter and grinding mill are illustrated by way of example. In the drawings- Fig. 1 is a vertical section of one and Fig. 2 a like view of the other form.

Referring to Fig. l, the pulp enters a circular sieve 3 through an inlet pipe or channel 2 disposed near the middle of the machine casing l. The sieve is provided at the top with a longitudinal opening il extending over the whole width of the machine through which the coarse stuff carried along by the blades or vanes 5 is thrown out of the machine while the sifted stuff liows away by a pipe 7, joined to the ma.- chine casino; The coarse stuff thrown out of the circular sieve 3 is deposited upon an inclined plane 8, and sliding along it drops into a grinding mill, disposed `fat the lower end and consisting of two almost contacting horizontal rollers 9, arranged in a horizontal plane within the casing l, between which rollers the coarse stuff is ground again. The troughs of the grinding rollers drop into the inlet channel 2 of the sifter and are sifted once more together with the fresh stuff. The rollers 9 are flushed with water in order to keep them clean :and to prevent chocking by adhering pulp. The sifting device and the grinding mill may either have a common drive or be driven separately.

rlhe combined machine illustrated in Fig. 2 is distinguished from the one before described only by the feature that the grinding mill consists of two stationary grind stones 10, 1Q and a rotating grind stone 11, and that the rotating stone is arranged upon and driven by the driving shaft 13 of the sifting machine.

The new combination offers the advantage that in the pulp factory at least one pump and the pipes required for it are rendered superfluous and thus not only a saving in the first cost of the plant and driving power is effected, but the spiace otherwise occupied by the pump and pipes is also made available for other purposes.

l claim:

1. A machine for grinding` and sifting wood pulp comprising a grinding device, a sieve, rotary means adapted to cooperate with said sieve for forcing the fines through the sieve and for ejecting the coarse stuff, a conduit leading from the exhaust side of said grinding device into said sieve and another conduit leading from said sieve back to the inlet side of saidgrinding device, the whole combined to form a self-contained unit.

2. A machine for grinding and sifting Wood pulp comprising a grinding device, a sieve, a longitudinal slotted sieve of substantially circular cross section, a rotary form an integral unit. 10 blade conveyor movable Within said sieve7 In testimony whereof l atiX my signa a conduit leading from the exhaust Side ture. of said grinding device into said sieve and another conduit, leading from the slot in said sieve back to the inlet side of said grinding device, the Whole combined to ANDREAS BIFFAR. 

